For reference, my backlash was about 0.1mm on the X slightly less Y, it doesn't sound like much and I think that is half the factory spec, but if my quick maths is right on a 2mm pitch screw, that translates to 18 degrees of movement in the hand wheel, which is pretty significant.

I consider 0.1 to be quite loose, I could have got it much lower without causing too greater increase in friction but I don't want to wear the screw out in the middle.

Wiess/Optimum have a slightly better manual available by searching online, but I think its much the same thing just clearer.

Edited By Russ B on 03/05/2015 12:25:58

The backlash can be adjusted a bit by tightening grub-screws in the split bronze female thread bosses – which are inside the base. Not a wonderful engineering solution, but …

Access is by removing the table. I have done this but I do not recall the exact details – it seemed to be fairly straightforward once you realise how to get the gib strips out. ie: endways from one end only when the large headed adjuster screws are removed. The strips are tapered lengthways so if you tap lightly and the table tightens up, that is the wrong end. You also need to remove one end handle of the X screw, I think the left one, and wind the table off.

I have a rather better manual from Optimus in Germany, – the Chester one is a photo-copy of some of this (ie with bits missing) but I have been told since that the Chester mill is not made by the same firm as Optimus's version.

If I can help further please ask

Regards, Tim

Personally I wouldn't worry about it. My mill has about 0.8mm of backlash on the Y-axis handle and 0.7mm on the X-axis handle. It's been a while since I adjusted the anti-backlash nuts, but all that generally happens is that the whole thing jams up at the ends of the travels if too much backlash is taken out in the middle. The backlash doesn't seem to affect my 'ability' to make parts that fit. To be fair though I do have a DRO.

Andrew